Wireless Design - Best Practices for Data, Voice, and LBS

Unanswered Question
Dec 16th, 2009


I am currently in the process of designing a WLAN for a new hospital and I am getting some push back from my sales team.  The requirements of the WLAN are data, voice, and location based services (RFID for medical equipment) ... needs to be 2.4 GHz for Guest and some apps/clients but primarily 5 GHz for most of the clients ... lastly needs to be N compatible for future use.

So, I did a predictive design with 1252's on the perimeter with 2.4 and 5 GHz patch antennas and 1142's in the middle to fill gaps ... I also scoped out 2 5508 for redundancy .... total design with -65 at my edges was 169.  However, this is getting push back because of several cost issues ....

1. The bundle that Cisco offers for 5 100 AP license 5508 WLC is cheaper than buying 2 250 AP licenses WLC's ... which doesn't make any sense to me because I think 5 devices is over kill

2. The sales engineer is concerned about the power issues with the 1252's ... customer would rather not use power injectors ... and although they would have 6500's at there core ... they would only have basic switches in their IDF's so I wasn't sure which POE Switches would be able to handle 1252 but cost was an issue there as well

So, for my understanding when you are doing a WLAN design for LBS it's always best to have APs or antennas on the perimeter for better triangulation ... it makes more sense to me to do that with patch instead of Omni's ... however my sales engineer wants to use all 1142's ... so my question is what are the pro and cons behind using all Omni's or using Patch and Omni's?

Furthermore, if anyone has any documentation supporting why I would not use all Omni's that would be great because all the articles I have read on LBS just state that placement of APs is critical but doesn't give no specifics on whether it's a good practice to place them on the perimeter using a specific type of antenna or what.

Thanks in advance for you help and any ideas about this design!!!

I have this problem too.
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Leo Laohoo Wed, 12/16/2009 - 16:03

1.  The 5508 is expensive because it's alot faster than the 4400 plus there are some features exclusive to the 5508 such as OfficeExtend.  As the old network design adage goes:  Your design can be done correctly, cheap or fast.  Choose two.

2.  The 1250 requires 19.5w of power to enable FULL MCS rates to both radios.  Only the 3560E, 3750E or the Sup720 is capable of supporting that.  Upgrading the IOS of the 1250 to 12.4(10b)JDA3 will allow the AP to operate both radios at 15.4w BUT at a lower MCS rates.  Correct placement of the AP and the correct use of the antennaes will also help in the signal distribution.

3.  Patch antennaes are mostly directional.  The 1140 is onmi-directional BUT the signal strength is not as powrful as the 1250 at full power.  The AIR-ANT2451NV is an omni-directional patch designed for the 1250.

Cisco Aironet Antennas and Accessories Reference Guide

Cisco Aironet 2.4 GHz and 5 GHz Antennas and Accessories

Some of the new patch antennaes for the 1250

Cisco Aironet Dual Band MIMO Low Profile Ceiling Mount Antenna (AIR-ANT2451NV-R)

Cisco Aironet Very Short 5-GHz Omnidirectional Antenna (AIR-ANT5135SDW-R)

Cisco Aironet Very Short 2.4-GHz Omnidirectional Antenna (AIR-ANT2422SDW-R)

Cisco Aironet 5-dBi Diversity Omnidirectional Antenna (AIR-ANT2452V-R)

Cisco Aironet 5-GHz MIMO Wall-Mounted Omnidirectional Antenna (AIR-ANT5140NV-R)

Cisco Aironet 5-GHz MIMO 6-dBi Patch Antenna (AIR-ANT5160NP-R)

Cisco Aironet 2.4-GHz MIMO Wall-Mounted Omnidirectional Antenna (AIR-ANT2450NV-R)

Cisco Aironet 2.4-GHz MIMO 6-dBi Patch Antenna (AIR-ANT2460NP-R)


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